Wish I had listened to oh what mama said
Wish I had listened to oh what mama said
Well I wouldn't be here trying to sleep in this cold iron bed

The earliest version by the Grateful Dead, on "Rare Cuts And Oddities" contains an extra verse:

I asked the judge now, what might be my fine
I asked the judge now, what might be my fine
Ninety years on the Rocky Island Line (note 3)

Notes(1) the sheet music has this line as
"Should I hear the lesson of what my mama say?"
But I'm pretty sure that's a mis-transcription.(2) similarly, the sheet music has "cold dark bed."(3) It originally sounded to me that Garcia sang "Rocky
Highland Line". But Ben Anderson pointed out to me that this was more
likely to be a reference to the Rock Island line, which makes sense. This stanza
normally appears in "Worried Man Blues", with some versions (eg by Mel Tillis)
having it as "Rocky Island Line". But many (eg the Carter Family, Ralph Stanley
etc) have it as "Rocky Mountain Line".

Roots
The original recording was by Cannon's Jug Stompers (Gus Cannon and Noah Lewis).
I don't know of any covers before the Grateful Dead's, so it seems likely they
learnt it off the original recording. The lyrics on that recording are very hard
to make out, and it may be that the Dead took took some of the lyrics from elsewhere:

Wish I had of listened, oh Lord, what mama said
Wish I had of listened, oh Lord, what mama said
Lord I wouldn't have been a [??]

Further Information
For an online discussion of the lyrics to this song see the deadsongs.vue conference on The Well.
For more information on recordings see Matt Schofield's Grateful Dead Family Discography
For sheet music, see:
Hundred Year Hall songbook (guitar TAB)